基于机动特征辅助的MFR状态预测方法

针对多功能雷达(Multi-Function Radar,MFR)状态预测方法存在的鲁棒性、预测正确率不佳的问题,提出一种基于机动特征辅助的MFR状态预测方法.该方法将载机机动信息与常规侦收参数共同作为预测特征集,一方面利用支持向量回归(Support Vector Regression,SVR)和侦收信号特征集,得到常规预测模型,另一方面通过SVR和机动特征集,得到MFR各个状态间的转变概率模型;然后利用D-S证据理论得到最终预测状态.实验结果表明,与SVR和LSR方法相比,平均预测精度分别提高了6.97%和7.2%,同时具备更优异的鲁棒性.此外,提出的预测方法通过进一步的拓展,可应用于机械设备、道路交通等领域.

海空背景下低慢小目标泛探雷达多域多维特征建模与分析

飞鸟和无人机等“低慢小”目标回波微弱、特征不明显,对雷达探测和识别提出了很高的要求,对其特征建模与特性分析是基础,而获取雷达多域多维的目标特征是前提。数字阵泛探雷达通过“宽发窄收”工作模式,实现目标的长时间积累,实现更高的积累增益和多普勒分辨率,能够获得目标的多域多维特征,为“低慢小”目标的精细化处理和探测识别一体化奠定了基础。该文针对海空背景下的飞鸟、旋翼和固定翼无人机、直升机等“低慢小”目标,利用数字阵泛探雷达系统获得的距离-方位-帧间、距离-脉冲-帧间等多维数据,提取目标的时域回波特征(单帧脉冲回波、动态脉冲回波)、变换域多普勒特征(多普勒瀑布图、微多普勒谱)、长时间机动特征(加速度序列、加加速度序列、航迹)7类19种多域多维特征,能够充分的反映目标在单帧和多帧数据间的幅值起伏、能量变化、运动、机动、微动等特性,从而实现对“低慢小”目标的精细化特性描述与分析。最后,采集并构建了数字阵泛探雷达“低慢小”目标特征数据集,对典型目标的特征进行验证和定量、定性分析,总结不同目标的特征差异,验证结果表明,四种类型的“低慢小”目标的多维特征具有明显的区别,获得的特征和差异将为后续的“低慢小”目标分类和识别提供重要支撑。

基于卡口数据的车辆特征及道路运行特征分析

机动车出行调查是城市交通调查中十分重要的内容,传统调查方法主要为人工观测方法,人力成本较大且获取信息较少。随着信息化管理水平不断提升,道路交通科技设施如电子警察/卡口等覆盖面越来越广,通过卡口识别的车辆位置数据可以实现对机动车出行轨迹进行全跟踪。基于C市主城区范围内的卡口数据,辅以道路网数据,主要利用数据统计分析、地图匹配和可视化等手段,提取机动车出行特征数据和道路网络运行情况,统计出的数据特征和结果基本符合C市交通出行规律,具备较好的可操作性和可复制性。

基于模式空间的群目标合并与分离方法研究

针对飞行编队形成的群目标航迹关联的特殊性,提出了群目标合并与分离涉及的4要素:位置、方向、机动曲率和航迹历史。在LHong构建的模式空间(即将量测数据序列由量测空间经小波变换映射到模式空间)的基础上,进一步提出了在模式空间利用其位置、指向、机动特征和航迹历史确定群目标合并与分离的新方法,即确定群目标成员的合法性方法。在模式空间经过Kalman滤波后再将模式空间变换到量测空间,以输出正确的量测。仿真结果证明了该算法的正确性与有效性。

Review on the proceeding of automatic seedlings classification by computer vision

The classification of seedlings is important to ensure the viability of seedlings after transplantation and is acknowledged as a key factor in forestation and environmental improvement. Based on numerous papers on automatic seedling classification (ASC), the seedling grading theory, traditional grading methods, the background and the proceeding of ASC techniques are described. The automation of the measurement of seedling morphological characteristics by photoelectric meters and computer vision is studied, and the automatic methods of the current grading systems are described respectively. And the further researches on ASC by computer vision are proposed.

Dynamics and screening characteristics of a vibrating screen with variable elliptical trace

The ideal motion characteristics for the vibrating screen was presented according to the principle of screening process with constant bed thickness.A new vibrating screen with variable elliptical trace was proposed.An accurate mechanical model was constructed according to the required structural motion features.Applying multi-degree-of-freedom vibration theory,characteristics of the vibrating screen was analyzed.Kinematics parameters of the vibrating screen which motion traces were linear,circular or elliptical were obtained.The stable solutions of the dynamic equations gave the motions of the vibrating screen by means of computer simulations.Technological parameters,including amplitude,movement velocity and throwing index,of five specific points along the screen surface were gained by theoretical calculation.The results show that the traces of the new designed vibrating screen follow the ideal screening motion.The screening efficiency and processing capacity may thus be effectively improved.

Motivation dimensions for running a marathon:A new model emerging from the Motivation of Marathon Scale(MOMS)

Purpose：The aim of this study was to test and expand the Motivation of Marathoners Scale（MOMS） model（Masters et al.,1993）.Methods：The MOMS questionnaire was distributed to 306 male and female marathon runners（age range：20–77 years） with experience in marathon running（range：1–44 runs）.A confirmatory factor analysis（CFA） revealed that the original Purpose：The aim of this study was to test and expand the Motivation of Marathoners Scale（MOMS） model（Masters et al.,1993）.Methods：The MOMS questionnaire was distributed to 306 male and female marathon runners（age range：20-77 years） with experience in marathon running（range：1-44 runs）.A confirmatory factor analysis（CFA） revealed that the original model failed to fit the data.Hence,exploratory factor analysis（EFA） was performed to test the best factorial solution for the current data,and a subsequent CFA was performed on the revised factorial structure.Then,a series of EFAs using maximum likelihood factor extraction method were performed.Results：The best structure solution for model-data fit resulted in 11 factors：psychological coping-emotional-related coping,psychological coping-everyday-life management,life meaning,self-esteem,recognition,affiliation,weight concerns,general health orientation-reduced disease prevalence and longevity,general health orientation-keep fit,competition,and personal goal achievement.Conclusion：This study provides a sound and solid framework for studying motivation for physically demanding tasks such as marathon runs,and needs to be similarly applied and tested in studies incorporating physical tasks which vary in mental demands.

Characteristics and failure mechanism of an ancient earthquake-induced landslide with an extremely wide distribution area

The Lamuajue landslide is located in Lamuajue village on the tight bank of the Meigu River, Sichuan Province, China. This landslide is an ancient landslide with an extremely wide distribution area, covering an area of 19 km2 with a maximum width of 5-5 km and an estimated residual volume of 3 × 108 ma. The objectives of this study were to identify the characteristics and failure mechanism of this landslide. In this study, based on field investigations, aerial photography, and profile surveys, the boundary, lithology, structure of the strata, and characteristics of the landslide deposits were determined. A gently angled weak interlayer consisting of shale was the main factor contributing to the occurrence of the Lamuajue landslide. The deposition area can be divided into three zones： zone A is an avalanche deposition area mainly composed of blocks, fragments, and debris with diameters ranging from o.i m to 3 m; zone B is a residual integrated rock mass deposition area with large blocks, boulders and ＂fake bedrock＂; and zone C is a deposition zone of limestone blocks and fragments. Three types of failure mechanism were analyzed and combined to explain the Lamuajue landslide based on the features of the accumulation area. First, a shattering-sliding mechanism caused by earthquakes in zone A. Second, a sliding mechanism along the weak intercalation caused by gravity and water in zone B. Third, a shattering-ejection mechanism generated by earthquakes in zone C. The results provide a distinctive case for the study of gigantic landslides induced by earthquakes, which is very important for understanding and assessing ancient earthquakeinduced landslides.

Vehicle Detection in Still Images by Using Boosted Local Feature Detector

Vehicle detectition in still images is a comparatively difficult task. This paper presents a method for this task by using boosted local pattern detector constructed from two local features including Haar-like and oriented gradient features. The whole process is composed of three stages. In the first stage, local appearance features of vehicles and non-vehicle objects are extracted. Haar-tike and oriented gradient features are extracted separately in this stage as local features. In the second stage, Adabeost algorithm is used to select the most discriminative features as weak detectors from the two local feature sets, and a strong local pattern detector is built by the weighted combination of these selected weak detectors. Finally, vehicle detection can be performed in still images by using the boosted strong local feature detector. Experiment results show that the local pattern detector constructed in this way combines the advantages of Haar-like and oriented gradient features, and can achieve better detection results than the detector by using single Haar-like features.

Long runout mechanism of the Shenzhen 2015 landslide:insights from a two-phase flow viewpoint

A catastrophic landslide occurred at Hongao dumpsite in Guangming New District of Shenzhen, South China, on December 20, 2015. An estimated total volume of 2.73×106 m3 of construction spoils was mobilized during this event. The landslide traveled a long distance on a low-relief terrain. The affected area was approximately 1100 m in length and 630 m in width. This landslide made 33 buildings destroyed, 73 people died and 4 people lost. Due to the special dumping history and other factors, soil in this landfill is of high initial water content. To identify the major factors that attribute to the long runout character, a two-phase flow model of Iverson and George was used to simulate the dynamics of this landslide. The influence of initial hydraulic permeability, initial dilatancy, and earth pressure coefficient was examined through numerical simulations. We found that pore pressure has the most significant effect on the dynamic characteristics of Shenzhen landslides. Average pore pressure ratio ofthe whole basal surface was used to evaluate the degree of liquefaction for the sliding material. The evolution and influence factors of this ratio were analyzed based on the computational results. An exponential function was proposed to fit the evolution curve of the average pore pressure ratio, which can be used as a reasonable and simplified evaluation of the pore pressure. This fitting function can be utilized to improve the single-phase flow model.

Study on Distributed Motion of Self-Reconfigurable Robot Based on Local Rules

The eigenvector of a module with six adjacent module's state was constructed according to self-reconfigurable robot M-Cubes and the configuration of system was expressed with the eigenvectors of all modules.According to the configuration and motion characteristics of the modules,a 3-dimension motion rule set was provided.The rule sets of each module was run according to eigenvector of the module after the motion direction of system decided and motion rules were selected.At last,the rapid and effective motion and metamorphosis were realized in system.The rule sets are operated on three systems and the distributed motion of system is fully realized.The result of simulation shows that the 3-dimension motion rule sets has perfect applicability and extensibility.The motion steps and communication load of the modules increase with the module number in linear.

Active Tracking with Pan-Tilt-Zoom Camera

This paper intends to introduce the active vision system with autonomous robot competition in the background. It presents some characteristics of the human oculomotor system in active ma-chine vision svstem: smooth pursuit and saccade. Besides, zoom tracking is used to continuous ad-justment of a camera's focal length to keep a constant sized image of an object moving along the camera's optical axis. Experiments indicate the technology to be efficient for tracking the bail in the robot competition.

Sparsity-Assisted Intelligent Condition Monitoring Method for Aero-engine Main Shaft Bearing

Weak feature extraction is of great importance for condition monitoring and intelligent diagnosis of aeroengine.Aimed at achieving intelligent diagnosis of aero-engine main shaft bearing,an enhanced sparsity-assisted intelligent condition monitoring method is proposed in this paper.Through analyzing the weakness of convex sparse model,i.e.the tradeoff between noise reduction and feature reconstruction,this paper proposes an enhanced-sparsity nonconvex regularized convex model based on Moreau envelope to achieve weak feature extraction.Accordingly,a sparsity-assisted deep convolutional variational autoencoders network is proposed,which achieves the intelligent identification of fault state through training denoised normal data.Finally,the effectiveness of the proposed method is verified through aero-engine bearing run-to-failure experiment.The comparison results show that the proposed method is good at abnormal pattern recognition,showing a good potential for weak fault intelligent diagnosis of aero-engine main shaft bearings.

Investigation of Structural System Safety

In order to investigate the behavior of buildings and engineering structures during earthquakes, based on the data of seismic observation devices mounted on constructions with typical characteristics, results of investigating the change of mechanical properties of building structural system over time and the results of examination of structural rigidity and safety change over time, depending on the dynamic characteristics of the building, determined by experimental investigations made at intervals are mentioned in this article. In addition, evaluation of earthquake acceleration acting on structures due to earthquake-induced damage characteristics of buildings and engineering constructions which are made earthquake resistant is also included here.

Analysis of characteristics of a pneumatic miniature robotic system

This paper described the structure of a flexible miniature robotic system which can move in human cavities, and then analyzed the characteristics of the robotic system in detail. The mobile mechanism of the miniature robotic system is soft; it makes inchworm-like movement driven by a 3-DOF pneumatic rubber actuator and holds its positions by air chambers. The driving characteristic models in axial and bending directions of the actuator were set up and the kinemics equations of the robotic system were set up. Experiments had been done through an electro-pressure control system, by which the pneumatic robotic system can be controlled with high accuracy. It is suitable for moving in human cavities for medical inspection.

Using Mixed Methods to Investigate the Relationship Between Student Motivation and Academic Achievement From Socio-Cultural Perspective

Language learning is a complex process for many reasons. First, it is closely related to linguistics. Second, language is social as it occurs within certain social contexts. And finally, it is individual. Personal characteristics such as experience, gender and age, attitude and aptitude, motivation, beliefs, self-confidence, and anxiety greatly influence language learning. Among these variables, motivation is considered to be one of the most important factors affecting the success of second or foreign language learning. However, the relationship between motivation and educational achievement is not quite clear. In the current literature, motivation is regarded as socially constructed, therefore as dynamic rather than static. Little research has been conducted on the motivation of Vietnamese students studying English as a compulsory curriculum component rather than as a major from a socio-cultural perspective. Understanding the relationship between student motivation and academic achievement as well as the socio-cultural factors that affect students＇ motivation will be an important contribution to motivation theory. Therefore, the situation requires longitudinal and in-depth research into student motivation, the factors affecting it during the learning process, and the relationship between student motivation and academic achievement. A mixed method approach has been chosen to meet the needs of the study. It is believed that insights in these areas will help address the issue of motivation at the Police University.

Vibration-based feature extraction of determining dynamic characteristic for engine block low vibration design

In order to maintain vibration performances within the limits of the design, a vibration-based feature extraction method for dynamic characteristic using empirical mode decomposition （EMD） and wavelet analysis was proposed. The proposed method was verified experimentally and numerically by implementing the scheme on engine block. In the implementation process, the following steps were identified to be important： 1） EMD technique in order to solve the feature extraction of vibration signals; 2） Vibration measurement for the purpose of confirming the structural weak regions of engine block in experiment; 3） Finite element modeling for the purpose of determining dynamic characteristic in time region and frequency region to affirm the comparability of response character corresponding to improvement schemes; 4） Adopting a feature index oflMF for structural improvement based on EMD and wavelet analysis. The obtained results show that IMF of signal is more sensitive to response character corresponding to improvement schemes. Finally, examination of the results confirms that the proposed vibration-based feature extraction method is very robust, and focuses on the relative merits of modification and full-scale structural optimization of engine, together with the creation of new low-vibration designs.

Characteristics of air quality in Tianjin during the Spring Festival period of 2015

To better understand the characteristics of air quality and the relationship between the chemical composition evolution and source variation,an intensive atmospheric campaign was conducted in Tianjin,a megacity of the North China Plain,from 10 February to 6 March 2015.There were 20 days exceeding the threshold value of secondary Chinese Ambient Air Quality Standards for PM2.5(75 μg m-3,daily average over 24 h)during the study period.Five air pollution episodes were selected for investigation.During the pre-holiday pollution episode,NH^+_4,NO^-_3,and SO^(2-)_4 were more abundant,indicating that air pollution was caused by motor vehicle exhaust emissions and coal consumption under unfavorable meteorological conditions.During Chinese Lunar New Year's Eve,widespread use of fireworks resulted in extremely high aerosol concentrations.Firework displays caused increases in K+ and also enrichment of SO^(2-)_4 relative to NO^-_3.The holiday pollution episode was caused by regional transport,characterized by abundant SO^(2-)_4 and NH^+_4.In addition,the aging processes of the particles from fireworks discharge played an important role in the formation of NO-3and SO^(2-)_4.The Lantern Festival episode was characterized by a transition from the enrichment of K+ to secondary inorganic ions(NO^-_3,SO^(2-)_4,and NH^+_4).The results of this study are useful for a detailed understanding of the variation in atmospheric compositions and sources caused by anthropogenic activity,and highlight the importance of controlling intensive fireworks discharge.

A Mixed Reality System for Investigating Expert Characteristics on Recall of Situation Including Self-Motion

To study recall accuracy of the offensive and defensive situations including movements of elite-athlete/novice oneself, a novel experimental system was developed where defensive actions were performed by the subject with a CG （Computer Graphics） player who presented predetermined offensive actions. Both the CG player＇s movements and subject＇s movements were reproduced by a video using mixed reality technology for recall examination. This system was also designed to rearrange the natural sequence of image frames resulting in a reproducible video in which the time relation of offense and defense was falsified. Displacement of timing in the false video was twofold; delayed from the truth or advanced from the truth. Using this two-video, true/false imagery method, the subject was asked to select the true video by recall; thus it became possible to examine the recall accuracy quantitatively by controlling the timing displacement. Results of the experiment using this system revealed that karate expert possessed a skill to recognize the time relation between the opponent＇s movement and one＇s own movement perceptually that was more developed than that of the novice. It was further identified that the expert as well as the novice recognized delayed displacement more accurately than they could recognize advanced displacement.

Fault diagnosis of rocket engine ground testing bed with self-organizing maps(SOMs)

To solve the fault diagnosis problem of liquid propellant rocket engine ground testing bed,a fault diagnosis approach based on self-organizing map(SOM)is proposed.The SOM projects the multidimensional ground testing bed data into a two-dimensional map.Visualization of the SOM is used to cluster the ground testing bed data.The out map of the SOM is divided to several regions.Each region is represented for one fault mode.The fault mode of testing data is determined according to the region of their labels belonged to.The method is evaluated using the testing data of a liquid-propellant rocket engine ground testing bed with sixteen fault states.The results show that it is a reliable and effective method for fault diagnosis with good visualization property.